1. Field of the Invention
The present invention relates to a heat engine, and in particular to a rotary style heat engine operating with increased efficiency.
2. Description of the Related Art
Heat energy, sometimes called thermal energy, is defines as the kinetic energy of a system's particles. Put another way, the heat energy of a system is the amount of potential energy in a system that is derived from the heat content within the system.
Temperature is not the same as heat energy. Yet, temperature makes up an integral part of the ideal gas law. The ideal gas law states:PV=nRT
Wherein:
P is Pressure
V is Volume
n is the amount of gas
R is the universal gas constant and
T is temperature
This ideal gas law demonstrates that temperature and pressure are directly related when the other variables are held constant. Likewise, when temperature is held constant in a closed system, the pressure and volume are inversely related.
This is demonstrated as follows:P1*V1=P2*V2
That is, the sum of pressure times volume stays constant in a closed system and when the temperature remains constant.
It is known that pressure within a system can be used to perform work. For example, in a properly designed system, potential energy of a high pressure container can be extracted by allowing a user to convert potential energy to kinetic energy.
As an example, consider a tank that is under pressure two times atmospheric pressure. The gas will rush out of the tank when a valve is opened until the pressures inside and outside of the tank equalize. Stating this differently, the gas inside the tank expands (from inside to outside the tank) until the pressures equalize. The expansion of the gas can be utilized to perform work.
There have been many engine designs over the years. One design is the Wankel, engine design. The Wankel engine is a four-cycle internal combustion engine that uses a rotating rotor motion instead of reciprocating pistons. The four cycles takes place between a Reuleaux triangle shaped rotor and an epitrochoid-shaped housing.
The housing can be defined as having 360 degrees of rotation. The rotor can generally be described as an equilateral triangle with rounded faces. The sum of internal angles of an equilateral triangle is 180 degrees. In this regard, the rotor revolves around an offset crankshaft wherein the apexes of the rotor contact the housing at all times. An example of this engine 5 design is shown in FIG. 1.
A single rotor engine is considered a three cylinder engine. In this regard, the space or volume between the apexes of the triangle and the housing wall define three chambers. Each chamber acts independently of the other chambers and each undergoes the intake, compression, ignition and exhaust cycles of the four-cycle design. Hence, three power cycles are produces by this engine.
The Wankel engine has been modified in many ways. Some modifications of the Wankel design, as well as examples of other designs are illustrated in the following patents and published application.
U.S. Pat. No. 3,426,525 to Rubin is titled Rotary Piston External Combustion Engine.
U.S. Pat. No. 3,509,718 to Fezer et al. is titled Hot Gas Machine.
U.S. Pat. No. 4,206,606 to Reich is titled Rotary Stirling Cycle Engine. It discloses a rotary Stirling cycle machine comprising at least two chambers, said chambers being epitrochoidal in cross-sectional area and having an upper portion, a middle waist portion and a lower portion, with the first chamber mounted to the second chamber in tandem, each chamber having a seal element attached to the waist portion and disposed inwardly, the crank shaft rotatably mounted within the chambers and extending therethrough with the first crank throw portion within the first chamber being 180.degree. out of phase with the second crank throw portion within the second chamber, the first and second rotor elements rotatably mounted on said respective crank throw portions with each rotor element being limicon shaped in circumference and adapted to register with the upper and lower portions of the respective chambers so that the rotor elements cyclically rotate about the rotating crank shaft from a position in registration with the upper portion to a position in registration with the lower portion, said seal elements being in constant sealing engagement with the respective rotor elements to define first cavities in the upper portions and second cavities in the lower portions, and heater-regenerator-cooler means operatively connected to said first and second cavities to condition a working fluid through repeated Stirling cycles.
U.S. Pat. No. 4,357,800 to Hecker is titled Rotary Heat Engine. It teaches a rotary external combustion heat engine for furnishing mechanical energy from a source of heat. The engine includes a ring-like stator having an oval rotor chamber enclosing a cylindrical rotor eccentrically placed within the chamber to define a high displacement high temperature fluid chamber and a lower displacement low temperature fluid chamber. A plurality of extensible vanes extend outwardly from the rotor in sliding contact with the inner surface of the rotor chamber. A source of heat supplies thermal energy to fluid supplied to the high temperature chamber, while a heat sink cools fluid supplied to the low temperature chamber. An economizer heat exchanger is also provided for preheating the working fluid. The relative position of the rotor within the rotor chamber is adjustable for varying the relative displacement of the fluid chambers to control engine working parameters. In another embodiment, a first heat engine is utilized as a motor and is mechanically coupled to a second heat engine utilized as a heat pump for providing an external combustion heat pump or refrigeration unit.
U.S. Pat. No. 4,760,701 to David is titled External Combustion Rotary Engine. The patent describes an external combustion rotary engine comprising a motor member, a free-piston combustion member and a storage tank serving also as a heat exchanger and located between the motor and the combustor. The motor rotors rotate inside an enveloping structure eccentrically with respect to a power shaft to form alternatively compression and expansion chambers. Compressed air produced thereby is ducted first to the storage tank and then to the combustor for burning fuel to produce combusted gases which are in turn ducted to the storage tank where heat is exchanged between the hot gases and the cooler compressed air. The combusted gas is then expanded in the expansion chambers. A fraction of the compressed air is further compressed to a higher pressure level so that it may be used in air pad cushions to isolate the various engine rotating parts from the fixed structures surrounding them. The use of such air cushions prevents contacts between moving parts and eliminates friction, heat production therefrom and wear. The need for lubrication is thus also eliminated. The “externally” performed fuel combustion is much slower than in comparable internal combustion rotary engines. This results in higher combustion efficiencies, lower combustion temperatures and lower rates of production of pollutants such as NO.sub.x.
U.S. Pat. No. 5,211,017 to Pusic is titled External Combustion Rotary Engine. It shows an external combustion rotary engine having a configuration which allows spatial separation of the heaters and coolers, and a process which enables rotary motion of the rotors to be performed without internal combustion. The engine includes the triangular rotors enclosed inside the housings shaped in the form of an epitrochoid curve, the heat generating units, and the heat absorbing and discharging units. The heat generating units and the heat absorbing and discharging units are located outside the housings and connected to the housings. The engine can also include the ultrasonic fuel atomizers inside the heat generating units and the turbine for the purpose of rapid acceleration. The present invention provides the simple, compact, lightweight, extremely energy-efficient and environmentally clean engine.
U.S. Pat. No. 5,325,671 to Boehling is titled Rotary Heat Engine. It describes an engine energized by an external heat source and cooled by an external cooling source, driven by a closed body of gas contained in chambers of variable volume and passages connected thereto, and operating on a Carnot cycle. The apparatus of the engine also has heat pump capabilities.
U.S. Pat. No. 6,109,040 to Ellison, Jr. et al. is titled Stirling Cycle Refrigerator or Engine employing the Rotary Wankel Mechanism. It illustrates a non-reciprocating Stirling-cycle machine which overcomes problems associated with high drive mechanism forces and vibration that seriously hamper reciprocating Stirling-cycle machines. The design employs Wankel rotors instead of the reciprocating pistons used in prior Stirling machines for effecting the compression and expansion cycles. Key innovations are the use of thermodynamic symmetry to allow coupling of the rotating compression and expansion spaces through simple stationary regenerators, and the coordination of thermodynamic and inertial phasing to allow complete balancing with one simple passive counterweight, which is not possible in reciprocating machines. The design can be scaled over a wide range of temperatures and capacities for use as a cryogenic or utilitarian refrigerator or to function as an external heat powered engine.
United States Patent Application Publication 2009/0139227 to Nakasuka et al. is titled Rotary Heat Device. It has a rotary heat engine having a cylinder and a rotor having a rotating shaft rotatably placed in the cylinder. The cylinder has a heat receiving section for supplying heat to the inside of the cylinder and a heat radiating section for radiating heat from the inside. The engine also has an engine section body and an operation liquid storage section. A vaporized gas supply channel and a gas recovery channel communicating with the inside of the cylinder are provided, respectively, on the heat receiving section side and heat radiating section side of the cylinder in the engine section body. The operation liquid storage section is between the vaporized gas supply channel and the gas collection channel in order to aggregate and liquefy recovered gas and is installed such that both channels fluidly communicate with each other. Also, the operation liquid storage section has a heat insulation dam provided with a through hole for preventing backflow of fluid flowing inside.
While each of these devices may be useful for their intended purposes, none show the unique advantages of the present invention.
Specifically none show an engine utilizing an elongated driving force due to opening of a valve when one of three apexes passes a prior exhaust port and the expansion chamber volume is small.
None show that an input valve can be closed at the appropriate timing whereby pressure in the expansion chamber and the pressure in the system outside of the expansion chamber will be approximately equal when the rotor leading apex passes the exhaust port.
Due to the geometry of adding a second inlet and exhaust ports, modified engines suffer from blow-by at certain times. The blow-by occurs as an expansion chamber will be open to both the inlet and exhaust simultaneously. None show the use of valves to prevent blow-by in a system having three apexes of a triangular rotor and two inlets and two exhaust ports spaced about the engine housing.
None show the use of fixed gates mounted in the housing to decrease expansion chamber volume and increase the portion of driving force about one side of a rotor as the rotor orbits about the housing center point.
Thus there exists a need for a heat engine that solves these and other problems.